Technical Abstract:
Antibiotic activities of indigenous microbes have been implicated in the development of disease suppressive soils and may play a role in pathogen inhibition in non-agricultural systems. However, little is known of the frequency, intensity, and diversity of antibiotic inhibition and resistance among indigenous microbes in prairie soil. The ability of Streptomyces isolates from prairie soil to inhibit and resist 10 standard Streptomyces isolates from a disease suppressive soil was evaluated. Analysis of antibiotic inhibition and resistance for individual isolates among 3 locations and 4 depths within a 1 m X 1 m plot revealed wide variation in inhibition and resistance. Fewer than 10 percent of isolates could inhibit or resist all 10 standards. One third of isolates were unable to inhibit any of the standards while no isolate was susceptible to all of the standards. The frequency and intensity of inhibition of the standards by indigenous Streptomyces isolates varied among locations and tended to increase with increasing depth. Resistance was highly variable among locations and depths, but no clear trends were evident.